Three-terminal capacitor

ABSTRACT

A capacitor element includes first through sixth surfaces, a first-side outer electrode at a first end portion of the first surface and on portions of the third, fifth, and sixth surfaces, a second-side outer electrode at a second end portion of the first surface and on portions of the fourth, fifth, and sixth surfaces, a center outer electrode at a portion of the first surface between the first-side outer electrode and the second-side outer electrode and on portions of the fifth and sixth surfaces, and two outermost conductor layers of first and second conductor layers are disposed at both outermost ends in the width direction, a first of the two outermost conductor layers next to one of the first conductor layers with an inner dielectric layer therebetween is connected to the center outer electrode, and a second of the pair of outermost conductor layers next to one of the second conductor layers with an inner dielectric layer therebetween is connected to the first-side outer electrode and the second-side outer electrode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a three-terminal capacitor.

2. Description of the Related Art

As electronic devices are becoming smaller and increasing theircapacitance, there is also an increasing demand for smaller andincreased-capacitance multilayer ceramic capacitors used in electronicdevices. Additionally, due to the provision of higher-frequency,lower-voltage, and lower-power-consumption electronic devices,multilayer ceramic capacitors having a small equivalent seriesinductance (ESL) are required. As an example of a multilayer ceramiccapacitor having a small ESL, a three-terminal ceramic capacitor isknown. In this three-terminal ceramic capacitor, the distance betweenouter electrodes is decreased so as to decrease the path through which acurrent flows, thereby reducing the inductance of the three-terminalceramic capacitor.

An example of such a three-terminal ceramic capacitor is disclosed inJapanese Unexamined Patent Application Publication No. 11-144996.

However, if the distance between outer electrodes is small, theinsulation resistance (IR) value between the side outer electrodes islikely to be reduced. Accordingly, a certain distance between outerelectrodes is required. However, if the position at which a paste forforming an outer electrode is applied is displaced, the distance betweenouter electrodes is decreased.

SUMMARY OF THE INVENTION

Accordingly, preferred embodiments of the present invention provide athree-terminal capacitor in which insulation resistance between outerelectrodes is less likely to be decreased since a distance between theside outer electrodes is maintained even if the position at which apaste for forming an outer electrode is applied is displaced.

According to a preferred embodiment of the present invention, athree-terminal capacitor includes a capacitor element including firstand second surfaces extending in a length direction and in a widthdirection, third and fourth surfaces extending in the width directionand in a thickness direction, and fifth and sixth surfaces extending inthe length direction and in the thickness direction; a first-side outerelectrode that is disposed at a first end portion of the first surfacein the length direction and on portions of the third, fifth, and sixthsurfaces; a second-side outer electrode that is disposed at a second endportion of the first surface in the length direction and on portions ofthe fourth, fifth, and sixth surfaces; a center outer electrode that isdisposed at a portion of the first surface between the first-side outerelectrode and the second-side outer electrode in the length directionand on portions of the fifth and sixth surfaces; a plurality of firstconductor layers that are disposed within the capacitor element and thatinclude first extending portions connected to the center outerelectrode; and a plurality of second conductor layers that are disposedwithin the capacitor element and that include first-side secondextending portions connected to the first-side outer electrode andsecond-side second extending portions connected to the second-side outerelectrode; wherein a pair of outermost conductor layers of the pluralityof the first conductor layers and the plurality of the second conductorlayers are disposed at both outermost ends in the width direction; afirst one of the pair of outermost conductor layers next to one of theplurality of first conductor layers with an inner dielectric layertherebetween is connected to the center outer electrode; and a secondone of the pair of outermost conductor layers next to one of theplurality of second conductor layers with an inner dielectric layertherebetween is connected to the first-side outer electrode and thesecond-side outer electrode.

In a preferred embodiment of the present invention, a three-terminalcapacitor includes an outer dielectric layer disposed adjacent to one ofthe fifth and sixth surfaces and next to one of the pair of outermostconductor layers; and a boundary layer including Mg and Mn is disposedbetween the outer dielectric layer and the one of the pair of outermostconductor layers.

In a three-terminal capacitor according to a preferred embodiment of thepresent invention, the one of the pair of outermost conductor layersincludes Ni; and the boundary layer includes Ni.

In a three-terminal capacitor according to a preferred embodiment of thepresent invention, at a cross section of the capacitor element, a ratioof a total length of conductor particles of one of the pair of outermostconductor layers to a length of the one of the pair of outermostconductor layers is smaller than a ratio of a total length of conductorparticles of a center conductor layer to a length of the centerconductor layer, the center conductor layer is closest to a center ofthe cross section of the capacitor element in the thickness directionamong the plurality of the first conductor layers and the plurality ofthe second conductor layers.

In a three-terminal capacitor according to a preferred embodiment of thepresent invention, at a cross section of the capacitor element, a ratioof a total length of conductor particles of one of the pair of outermostconductor layers to a length of the one of the pair of outermostconductor layers is smaller than a ratio of a total length of conductorparticles of a center conductor layer to a length of the centerconductor layer, the center conductor layer is closest to a center inthe thickness direction of the cross section of the capacitor elementamong the plurality of the first conductor layers and the plurality ofthe second conductor layers.

In a three-terminal capacitor according to a preferred embodiment of thepresent invention, the conductor particles of the one of the pair ofoutermost conductor layers include Ni; and the conductor particles ofthe center conductor layer include Ni.

In a three-terminal capacitor according to a preferred embodiment of thepresent invention, a material is provided within the capacitor element,the material couples dielectric layers with one of the pair of outermostconductor layers located therebetween and includes at least one of Si,Al and BaTiO₃.

In a three-terminal capacitor according to a preferred embodiment of thepresent invention, the plurality of second conductor layers are exposedat the first surface and are connected to the first-side outer electrodeand the second-side outer electrode at the first surface; and theplurality of second conductor layers are spaced apart from the third andfourth surfaces.

In a three-terminal capacitor according to a preferred embodiment of thepresent invention, the second one of the pair of outermost conductorlayers is exposed at the first surface and is connected to thefirst-side outer electrode and the second-side outer electrode at thefirst surface; and the second one of the pair of outermost conductorlayers is spaced apart from the third and fourth surfaces.

In a three-terminal capacitor according to a preferred embodiment of thepresent invention, a length of the first-side outer electrode in thelength direction is E1; a length of the second-side outer electrode inthe length direction is E3; a length of the center outer electrode inthe length direction is E2; a width from an edge of the first-sidesecond extending portion closer to the third surface to the thirdsurface is M1L; a width from an edge of the first-side second extendingportion closer to the fourth surface to an edge of the first-side outerelectrode on the first surface is M1R; a width from an edge of the firstextending portion closer to the third surface to an edge of the centerouter electrode on the first surface closer to the third surface is M2L;a width from an edge of the first extending portion closer to the fourthsurface to an edge of the center outer electrode on the first surfacecloser to the fourth surface is M2R; a width from an edge of thesecond-side second extending portion closer to the fourth surface to thefourth surface is M3R; a width from an edge of the second-side secondextending portion closer to the third surface to an edge of thesecond-side outer electrode on the first surface is M3L; and E1<E2,E3<E2, M2L<M2R, M1L<M1R, and M3L<M3R are satisfied.

According to various preferred embodiments of the present invention, itis possible to provide three-terminal capacitors in which insulationresistance between outer electrodes is less likely to be decreased sincethe distance between the outer electrodes is maintained even if theposition at which a paste for forming an outer electrode is applied isdisplaced.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external perspective view of a three-terminal capacitoraccording to a first preferred embodiment of the present invention.

FIG. 2 is a perspective view of a capacitor element of thethree-terminal capacitor shown in FIG. 1.

FIG. 3 is an exploded perspective view of the capacitor element shown inFIG. 2.

FIG. 4 is an external perspective view of a modified example of thethree-terminal capacitor of the first preferred embodiment of thepresent invention.

FIG. 5 is a perspective view of a modified example of the capacitorelement shown in FIG. 2.

FIG. 6 is a schematic view of extending portions of inner electrodesdisposed on a mounting surface of the capacitor element shown in FIG. 5.

FIG. 7 illustrates a first inner electrode and first extending portionsof the capacitor element shown in FIG. 5.

FIG. 8 illustrates a second inner electrode and second extendingportions of the capacitor element shown in FIG. 5.

FIGS. 9A and 9B are schematic sectional views of another modifiedexample of the three-terminal capacitor shown in FIG. 1.

FIG. 10 is a schematic front view of a fifth surface of a capacitorelement of another modified example of the three-terminal capacitor ofthe first preferred embodiment of the present invention.

FIGS. 11A and 11B are schematic sectional views taken along lines VI-VIand VII-VII, respectively, of FIG. 10.

FIG. 12 illustrates the interface between an outer dielectric layer andan outermost conductor layer with a boundary layer therebetween.

FIGS. 13A and 13B are schematic sectional views of the three-terminalcapacitor of the first preferred embodiment of the present invention.

FIG. 14 is an external perspective view of a three-terminal capacitoraccording to a second preferred embodiment of the present invention.

FIG. 15 is a perspective view of a capacitor element of thethree-terminal capacitor shown in FIG. 14.

FIG. 16 is an exploded perspective view of the capacitor element shownin FIG. 15.

FIG. 17 is an external perspective view of a modified example of thethree-terminal capacitor of the second preferred embodiment of thepresent invention shown in FIG. 14.

FIG. 18 is a perspective view of a modified example of the capacitorelement shown in FIG. 15.

FIG. 19 illustrates a first inner electrode and a first extendingportion of the capacitor element shown in FIG. 18.

FIG. 20 illustrates a second inner electrode and second extendingportions of the capacitor element shown in FIG. 18.

FIGS. 21A and 21B are schematic sectional views of another modifiedexample of the three-terminal capacitor shown in FIG. 14.

FIG. 22 is a flowchart illustrating an example of a manufacturing methodfor a three-terminal capacitor according to a preferred embodiment ofthe present invention.

FIGS. 23A and 23B illustrate a method for calculating an R amount ofridge lines.

FIGS. 24A through 24C are schematic diagrams illustrating a path throughwhich a signal and noise are transmitted when a three-terminal capacitorof a preferred embodiment of the present invention is used with a thefirst pattern.

FIGS. 25A through 25C are schematic diagrams illustrating a path throughwhich a signal and noise are transmitted when a three-terminal capacitorof a preferred embodiment of the present invention is used with a secondpattern.

FIG. 26 is a graph illustrating frequency characteristics concerning theinsertion loss when a three-terminal capacitor of a preferred embodimentis used with the first pattern and those when a three-terminal capacitorof a preferred embodiment is used with the second pattern.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Preferred Embodiment

FIG. 1 is an external perspective view of a three-terminal capacitor100. FIG. 2 is a perspective view of a capacitor element 102 of thethree-terminal capacitor 100 shown in FIG. 1. FIG. 3 is an explodedperspective view of the capacitor element 102 shown in FIG. 2.

The three-terminal capacitor 100 includes a capacitor element 102preferably having a rectangular or substantially rectangularparallelepiped configuration, center outer electrodes 104 and 105located at the central portion of the surfaces of the capacitor element102, and outer electrodes 106, 107, 108, and 109 located at the rightand left end portions of the surfaces of the capacitor element 102.

The capacitor element 102 includes first and second surfaces 102 a and102 b opposing each other in a thickness direction (top-bottomdirection) T. The capacitor element 102 also includes third and fourthsurfaces 102 c and 102 d opposing each other in a length direction(right-left direction) L. The capacitor element 102 also includes fifthand sixth surfaces 102 e and 102 f opposing each other in a widthdirection (front-back direction) W.

The dimension of the three-terminal capacitor 100 in the lengthdirection L is preferably about 2.00 to about 2.10 mm, the dimension inthe thickness direction T is preferably about 0.7 to about 1.0 mm, andthe dimension in the width direction W is preferably about 1.20 to about1.40 mm, for example.

The dimensions of the three-terminal capacitor 100 in the lengthdirection L, the thickness direction T, and the width direction W may bemeasured by using a micrometer MDC-25MX made by Mitutoyo Corporation,for example.

The center outer electrode 104 extends from the longitudinal centralportion of the first surface 102 a to the fifth and sixth surfaces 102 eand 102 f. The center outer electrode 105 extends from the longitudinalcentral portion of the second surface 102 b to the fifth and sixthsurfaces 102 e and 102 f.

The center outer electrode 104 includes a center outer electrode body104 a and first portions 104 b, 104 b. The center outer electrode body104 a is electrically connected to a first extending portion 132 of afirst conductor layer 120, which will be discussed later. The firstportions 104 b, 104 b extend from both ends of the center outerelectrode body 104 a. Accordingly, the center outer electrode body 104 ais located on the first surface 102 a, and the first portions 104 b, 104b are located on the fifth and sixth surfaces 102 e and 102 f.

Similarly, the center outer electrode 105 includes a center outerelectrode body 105 a and first portions 105 b, 105 b. The center outerelectrode body 105 a is electrically connected to a first extendingportion 133 of the first conductor layer 120, which will be discussedlater. The first portions 105 b, 105 b extend from both ends of thecenter outer electrode body 105 a. Accordingly, the center outerelectrode body 105 a is located on the second surface 102 b, and thefirst portions 105 b, 105 b are located on the fifth and sixth surfaces102 e and 102 f.

The side outer electrodes 106 and 108 are respectively disposed at theleft and right end portions of the first surface 102 a with the centerouter electrode 104 therebetween.

More specifically, the side outer electrode 106 extends from onelongitudinal end of the first surface 102 a to the third, fifth, andsixth surfaces 102 c, 102 e, and 102 f. The side outer electrode 108extends from the other longitudinal end of the first surface 102 a tothe fourth, fifth, and sixth surfaces 102 d, 102 e, and 102 f.

The side outer electrode 106 includes an outer electrode body 106 a,second portions 106 b, 106 b, and a third portion 106 c. The side outerelectrode body 106 a is electrically connected to a second extendingportion 134 of a second conductor layer 122, which will be discussedlater. The second portions 106 b, 106 b extend from both ends of theside outer electrode body 106 a. The third portion 106 c extends fromone side (toward the third surface 102 c) of the side outer electrodebody 106 a. Accordingly, the side outer electrode body 106 a is locatedon the first surface 102 a, the second portions 106 b, 106 b are locatedon the fifth and sixth surfaces 102 e and 102 f, and the third portion106 c is located on the third surface 102 c.

Similarly, the side outer electrode 108 includes an outer electrode body108 a, second portions 108 b, 108 b, and a third portion 108 c. The sideouter electrode body 108 a is electrically connected to a secondextending portion 136 of the second conductor layer 122, which will bediscussed later. The second portions 108 b, 108 b extend from both endsof the side outer electrode body 108 a. The third portion 108 c extendsfrom the other side (toward the fourth surface 102 d) of the side outerelectrode body 108 a. Accordingly, the side outer electrode body 108 ais located on the first surface 102 a, the second portions 108 b, 108 bare located on the fifth and sixth surfaces 102 e and 102 f, and thethird portion 108 c is located on the fourth surface 102 d.

The side outer electrodes 107 and 109 are respectively disposed at theleft and right end portions of the second surface 102 b with the centerouter electrode 105 therebetween.

More specifically, the side outer electrode 107 extends from onelongitudinal end of the second surface 102 b to the third, fifth, andsixth surfaces 102 c, 102 e, and 102 f. The side outer electrode 109extends from the other longitudinal end of the second surface 102 b tothe fourth, fifth, and sixth surfaces 102 d, 102 e, and 102 f.

The side outer electrode 107 includes an outer electrode body 107 a,second portions 107 b, 107 b, and a third portion 107 c. The side outerelectrode body 107 a is electrically connected to a second extendingportion 135 of the second conductor layer 122, which will be discussedlater. The second portions 107 b, 107 b extend from both ends of theside outer electrode body 107 a. The third portion 107 c extends fromone side (toward the third surface 102 c) of the side outer electrodebody 107 a. Accordingly, the side outer electrode body 107 a is locatedon the second surface 102 b, the second portions 107 b, 107 b arelocated on the fifth and sixth surfaces 102 e and 102 f, and the thirdportion 107 c is located on the third surface 102 c.

Similarly, the side outer electrode 109 includes an outer electrode body109 a, second portions 109 b, 109 b, and a third portion 109 c. The sideouter electrode body 109 a is electrically connected to a secondextending portion 137 of the second conductor layer 122, which will bediscussed later. The second portions 109 b, 109 b extend from both endsof the side outer electrode body 109 a. The third portion 109 c extendsfrom the other side (toward the fourth surface 102 d) of the side outerelectrode body 109 a. Accordingly, the side outer electrode body 109 ais located on the second surface 102 b, the second portions 109 b, 109 bare located on the fifth and sixth surfaces 102 e and 102 f, and thethird portion 109 c is located on the fourth surface 102 d.

With the above-described configuration, one of the first or secondsurface 102 a or 102 b defines and serves as a mounting surface of thethree-terminal capacitor 100.

In this case, a width B of each of the center outer electrodes 104 and105 preferably is greater than a width A of each of the side outerelectrodes 106 through 109. More specifically, the width B of each ofthe center outer electrodes 104 and 105 preferably is about 0.63 toabout 0.67 mm, while the width A of each of the side outer electrodes106 through 109 is about 0.35 to about 0.45 mm, for example.

The width B of each of the center outer electrodes 104 and 105 and thewidth A of each of the side outer electrodes 106 through 109 may bemeasured by projecting the first or second surface 102 a or 102 b of thethree-terminal capacitor 100 at a magnifying power of 20 by using ameasuring microscope MM-60 made by Nikon Corporation, for example.

Each of the center outer electrodes 104 and 105 preferably has a desiredthickness by applying a paste once, while each of the side outerelectrodes 106 through 109 preferably has a desired thickness byapplying a paste twice, for example. As a result, the thickness of theside outer electrodes 106 through 109 is greater than that of the centerouter electrodes 104 and 105.

The thickness of each of the center outer electrodes 104 and 105 and thethickness of each of the side outer electrodes 106 through 109 may bemeasured as follows. By polishing the fifth surface 102 e of thethree-terminal capacitor 100 toward the center of the width direction,cross sections of the center outer electrodes 104 and 105 and the sideouter electrodes 106 through 109 are exposed. Then, after edge roundingcaused by polishing is removed, the cross sections of the center outerelectrodes 104 and 105 and the side outer electrodes 106 through 109 areprojected so as to measure the thicknesses thereof.

In this manner, by forming the thickness of the side outer electrodes106 through 109 to be greater than that of the center outer electrodes104 and 105, the three-terminal capacitor 100 is capable of beingmounted on a mount board in parallel or substantially in parallel witheach other. As a result, the height of the three-terminal capacitor 100mounted on a mount board is not increased.

FIG. 4 is an external perspective view of a modified example of thethree-terminal capacitor 100 shown in FIG. 1.

In the three-terminal capacitor 100A shown in FIG. 4, a width B′ of eachof the first portions 104 b and 105 b of the center outer electrodes 104and 105, respectively, is greater than a width B of each of the centerouter electrode bodies 104 a and 105 a of the center outer electrodes104 and 105, respectively. Similarly, a width A′ of each of the secondportions 106 b through 109 b of the side outer electrodes 106 through109, respectively, is greater than a width A of the side outer electrodebodies 106 a through 109 a of the side outer electrodes 106 through 109,respectively. That is, the width B′ of each of the first portions 104 band 105 b of the center outer electrodes 104 and 105 and the width A′ ofeach of the second portions 106 b through 109 b of the side outerelectrodes 106 through 109 are respectively longer in the lengthdirection L than the width B of each of the center outer electrodebodies 104 a and 105 a and the width A of each of the side outerelectrode bodies 106 a through 109 a.

In this case, the width B′ of the first portion 104 b of the centerouter electrode 104 is maximized at a boundary portion 103 a at whichthe first surface 102 a intersects with the fifth surface 102 e and at aboundary portion 103 b at which the first surface 102 a intersects withthe sixth surface 102 f. Similarly, the width A′ of each of the secondportions 106 b and 108 b of the side outer electrodes 106 and 108 ismaximized at the boundary portions 103 a and 103 b.

The width B′ of the first portion 105 b of the center outer electrode105 is maximized at a boundary portion 103 c at which the second surface102 b intersects with the fifth surface 102 e and at a boundary portion103 d at which the second surface 102 b intersects with the sixthsurface 102 f. Similarly, the width A′ of each of the second portions107 b and 109 b of the side outer electrodes 107 and 109 is maximized atthe boundary portions 103 c and 103 d.

As discussed above, if the width B′ of each of the first portions 104 band 105 b of the center outer electrodes 104 and 105 is greater than thewidth B of each of the center outer electrode bodies 104 a and 105 a ofthe center outer electrodes 104 and 105, and if the width A′ of each ofthe second portions 106 b through 109 b of the side outer electrodes 106through 109 is greater than the width A of each of the side outerelectrode bodies 106 a through 109 a of the side outer electrodes 106through 109, it is possible to increase the amount of solder that is wetand is suitably bonded with the first portions 104 b and 105 b and withthe second portions 106 b through 109 b. Accordingly, the area offillets formed by solder at the lands of a mount board is decreasedwhile maintaining the bonding strength between the three-terminalcapacitor 100A and the mount board. Thus, by mounting the three-terminalcapacitor 100A configured as described above on a mount board, the areaof land patterns of the mount board is capable of being significantlyreduced.

Referring back to FIG. 1, concerning the side outer electrode 106disposed at one end portion of the first surface 102 a in the lengthdirection L, if the higher one of the heights of the longitudinalcentral portions of the second portions 106 b, 106 b disposed on thefifth and sixth surfaces 102 e and 102 f is indicated by H2 and if theheight of the widthwise central portion of the third portion 106 cdisposed on the third surface 102 c is indicated by H3, the relationshipbetween the heights H2 and H3 preferably satisfies H2>H3.

Concerning the side outer electrode 108 disposed at the other endportion of the first surface 102 a in the length direction L, if thehigher one of the heights of the longitudinal central portions of thesecond portions 108 b, 108 b disposed on the fifth and sixth surfaces102 e and 102 f is indicated by H2′ and if the height of the widthwisecentral portion of the third portion 108 c disposed on the fourthsurface 102 d is indicated by H3′, the relationship between the heightsH2′ and H3′ preferably satisfies H2′>H3′.

Concerning the side outer electrode 107 disposed at one end portion ofthe second surface 102 b in the length direction L, if the higher one ofthe heights of the longitudinal central portions of the second portions107 b, 107 b disposed on the fifth and sixth surfaces 102 e and 102 f isindicated by H2 and if the height of the widthwise central portion ofthe third portion 107 c disposed on the third surface 102 c is indicatedby H3, the relationship between the heights H2 and H3 preferablysatisfies H2>H3.

Concerning the side outer electrode 109 disposed at the other endportion of the second surface 102 b in the length direction L, if thehigher one of the heights of the longitudinal central portions of thesecond portions 109 b, 109 b disposed on the fifth and sixth surfaces102 e and 102 f is indicated by H2′ and if the height of the widthwisecentral portion of the third portion 109 c disposed on the fourthsurface 102 d is indicated by H3′, the relationship between the heightsH2′ and H3′ preferably satisfies H2′>H3′.

The three-terminal capacitor 100 preferably satisfies the relationshipsH2>H3 and H2′>H3′, as discussed above. Thus, when the three-terminalcapacitor 100 is mounted on a mount board by using the first surface 102a as a mounting surface, the amount of solder that is wet and issuitably bonded with the second portions 106 b and 108 b of the sideouter electrodes 106 and 108 is greater than the amount of solder thatis wet and is suitably bonded with the third portions 106 c and 108 c ofthe side outer electrodes 106 and 108. Accordingly, the positionaldisplacement of the three-terminal capacitor 100 is significantlyreduced or prevented, and the bonding strength between thethree-terminal capacitor 100 and the mount board is also maintained.

The center outer electrodes 104 and 105 and the side outer electrodes106 through 109 are preferably made of Ag, Cu, Ni, Pd, or an alloy ofsuch metals. Additionally, a plating film is preferably located on thesurface of each of the center outer electrodes 104 and 105 and the sideouter electrodes 106 through 109. The plating film protects the centerouter electrodes 104 and 105 and the side outer electrodes 106 through109 and also improves the solderability of the center outer electrodes104 and 105 and the side outer electrodes 106 through 109.

The center outer electrodes 104 and 105 may be used as groundelectrodes, while the side outer electrodes 106 through 109 may be usedas signal electrodes, and vice versa.

As shown in FIG. 3, the capacitor element 102 preferably has amultilayer structure including, in the width direction W (stackingdirection), a plurality of inner dielectric layers 110, a plurality offirst and second conductor layers 120 and 122 which are each disposed atthe interface between inner dielectric layers 110, outermost conductorlayers 124 and 126 disposed such that they sandwich the plurality ofinner dielectric layers 110 therebetween, and outer dielectric layers112 disposed such that they sandwich the outermost conductor layers 124and 126 therebetween.

The first conductor layers 120 each include a first opposing portion 128and first extending portions 132 and 133 respectively extending from thecentral portion of the first opposing portion 128 downward and upward inthe thickness direction T. The first extending portion 132 extends tothe central portion of the first surface 102 a of the capacitor element102 and is exposed at the central portion so as to be electricallyconnected to the center outer electrode 104. The first extending portion133 extends to the central portion of the second surface 102 b of thecapacitor element 102 and is exposed at the central portion so as to beelectrically connected to the center outer electrode 105.

The second conductor layers 122 each have a second opposing portion 130,second extending portions 134 and 135 respectively extending from theleft end portion of the second opposing portion 130 downward and upwardin the thickness direction T, and second extending portions 136 and 137respectively extending from the right end portion of the second opposingportion 130 downward and upward in the thickness direction T. The secondextending portion 134 extends to the left end portion of the firstsurface 102 a of the capacitor element 102 and is exposed at the leftend portion so as to be electrically connected to the side outerelectrode 106. The second extending portion 135 extends to the left endportion of the second surface 102 b of the capacitor element 102 and isexposed at the left end portion so as to be electrically connected tothe side outer electrode 107. The second extending portion 136 extendsto the right end portion of the first surface 102 a of the capacitorelement 102 and is exposed at the right end portion so as to beelectrically connected to the side outer electrode 108. The secondextending portion 137 extends to the right end portion of the secondsurface 102 b of the capacitor element 102 and is exposed at the rightend portion so as to be electrically connected to the side outerelectrode 109.

FIG. 5 is a perspective view of a modified example of the capacitorelement 102 shown in FIG. 2. FIG. 6 is a schematic view of extendingportions of inner electrodes (conductor layers) disposed on a mountingsurface of the capacitor element 102A shown in FIG. 5. FIG. 7illustrates a first inner electrode (first conductor layer 120) and thefirst extending portions 132 and 133 of the capacitor element 102A shownin FIG. 5. FIG. 8 illustrates a second inner electrode (second conductorlayer 122) and the second extending portions 134 through 137 of thecapacitor element 102A shown in FIG. 5.

Part (I) of FIG. 7 illustrates the first conductor layer 120 and thefirst extending portions 132 and 133 taken along line I-I (position inthe vicinity of the outermost layer of the capacitor element 102A) ofFIG. 5 (perspective view) and FIG. 6 (schematic view). Part (II) of FIG.7 illustrates the first conductor layer 120 and the first extendingportions 132 and 133 taken along line II-II (position in the vicinity ofa layer disposed farther inward than the outermost layer of thecapacitor element 102A by about ¼ of the width W) of FIGS. 5 and 6.Hereinafter, the layer shown in part (II) of FIG. 7 will be referred toas a “¼ layer”). Part (III) of FIG. 7 illustrates the first conductorlayer 120 and the first extending portions 132 and 133 taken along lineIII-III (position in the vicinity of a layer disposed farther inwardthan the outermost layer of the capacitor element 102A by about ½ of thewidth W) of FIGS. 5 and 6. Hereinafter, the layer shown in part (III) ofFIG. 7 will be referred to as a “center layer”).

A width E of the exposed portions of the first extending portions 132and 133 of the first conductor layer 120 disposed near the center layerof the capacitor element 102A is preferably greater than a width F ofthe exposed portions of the first extending portions 132 and 133 of thefirst conductor layer 120 disposed near the outermost layer of thecapacitor element 102A. The width of the exposed portions of the firstextending portions 132 and 133 is gradually increased from the positionnear the outermost layer to the position near the center layer.

Part (I) of FIG. 8 illustrates the second conductor layer 122 and thesecond extending portions 134 through 137 taken along line I-I of FIGS.5 and 6. Part (II) of FIG. 8 illustrates the second conductor layer 122and the second extending portions 134 through 137 taken along line II-IIof FIGS. 5 and 6. Part (III) of FIG. 8 illustrates the second conductorlayer 122 and the second extending portions 134 through 137 taken alongline III-III of FIGS. 5 and 6.

A width G of the exposed portions of the second extending portions 134through 137 of the second conductor layer 122 disposed near the centerlayer of the capacitor element 102A is preferably greater than a width Hof the exposed portions of the second extending portions 134 through 137of the second conductor layer 122 disposed near the outermost layer ofthe capacitor element 102A. The width of the exposed portions of thesecond extending portions 134 through 137 is gradually increased fromthe position near the outermost layer to the position near the centerlayer.

As shown in FIG. 6, the exposed portions of the second extendingportions 134 and 135 of the second conductor layer 122 disposed near thecenter layer of the capacitor element 102A are separated from the thirdsurface (end surface) 102 c of the capacitor element 102A by a distanceC. Similarly, the exposed portions of the second extending portions 136and 137 of the second conductor layer 122 disposed near the center layerof the capacitor element 102A is separated from the fourth surface (endsurface) 102 d of the capacitor element 102A by a distance C. Meanwhile,the exposed portions of the second extending portions 134 and 135 of thesecond conductor layer 122 disposed near the outermost layer of thecapacitor element 102A are separated from the third surface 102 c of thecapacitor element 102A by a distance D. Similarly, the exposed portionsof the second extending portions 136 and 137 of the second conductorlayer 122 disposed near the outermost layer of the capacitor element102A are separated from the fourth surface 102 d of the capacitorelement 102A by a distance D. The distance D is preferably greater thanthe distance C.

In order to set the distance D to be greater than the distance C, thesecond extending portions 134 through 137 are preferably configured asfollows. As shown in FIG. 8, the second extending portions 134 through137 of the second conductor layer 122 disposed near the outermost layerof the capacitor element 102A each include an oblique section 129, sothat the exposed portions of the second extending portions 134 through137 are positioned toward the center (inward). Then, by setting theangle of the oblique section 129 to increase from the position of thesecond conductor layer 122 near the outermost layer to the position ofthe second conductor layer 122 near the center layer, the positions ofthe exposed portions of the second extending portions 134 through 137are shifted gradually toward outward.

Table 1 indicates examples of specific numeric values of the distancesbetween the exposed portions of the second extending portions 134 and135 (second extending portions 136 and 137) and the third surface 102 c(fourth surface 102 d) of the capacitor element 102A, the widths of theexposed portions of the second extending portions 134 through 137, andthe widths of the exposed portions of the first extending portions 132and 133, at the position of line I-I (position near the outermostlayer), the position of line II-II, and the position of line III-III(position near the center layer) of FIG. 6. In Table 1, α is a numericvalue equal to the distance C between the exposed portions of the secondextending portions 134 and 135 (second extending portions 136 and 137)near the center layer and the third surface 102 c (fourth surface 102 d)of the capacitor element 102A.

TABLE 1 Distance between Width of Width of exposed portions of exposedexposed second extending portions of portions of portions and end secondfirst surfaces of extending extending capacitor element portionsportions Position of line I-I α + 40 μm(=D) 230 μm(=H) 460 μm(=F)Position of II-II α + 20 μm 240 μm 480 μm Position of III-III α μm(=C)250 μm(=G) 500 μm(=E)

By setting the distance D to be greater than the distance C in thismanner, it is possible to obtain a three-terminal capacitor 100 in whichcracks are less likely to occur near the outermost layer of thecapacitor element 102A.

If the width G of the exposed portion of the second extending portions134 through 137 of the second conductor layer 122 disposed near thecenter layer of the capacitor element 102A is preferably greater thanthe width H of the exposed portion of the second extending portions 134through 137 of the second conductor layer 122 disposed near theoutermost layer of the capacitor element 102A, cracks are even lesslikely to occur near the outermost layer of the capacitor element 102A.

If the width E of the exposed portions of the first extending portions132 and 133 of the first conductor layer 120 disposed near the centerlayer of the capacitor element 102A is preferably greater than the widthF of the exposed portions of the first extending portions 132 and 133 ofthe first conductor layer 120 disposed near the outermost layer of thecapacitor element 102A, the electrical distance between the center outerelectrodes 104 and 105 and the side outer electrodes 106 through 109near the center of the capacitor element 102A is decreased so as to beequal or substantially equal to the electrical distance between thecenter outer electrodes 104 and 105 and the side outer electrodes 106through 109 near the outermost layer of the capacitor element 102A. As aresult, the equivalent series inductance (ESL) becomes uniform, andalso, it is decreased.

FIGS. 9A and 9B are schematic sectional views of another modifiedexample of the three-terminal capacitor 100 shown in FIG. 1.

As shown in FIG. 9A, the first extending portion 132 may include adouble-sided oblique section 170 a at a position closer to the firstopposing portion 128 and a straight-line section 170 b at a positioncloser to the first surface 102 a. The double-sided oblique section 170a extends obliquely in two directions toward the second extendingportions 134 and 136. Similarly, the first extending portion 133 mayinclude a double-sided oblique section 171 a at a position closer to thefirst opposing portion 128 and a straight-line section 171 b at aposition closer to the second surface 102 b. The double-sided obliquesection 171 a extends obliquely in two directions toward the secondextending portions 135 and 137.

As shown in FIG. 9B, the second extending portion 134 may include asingle-sided oblique section 172 a at a position closer to the secondopposing portion 130 and a straight-line section 172 b at a positioncloser to the first surface 102 a. The single-sided oblique section 172a extends obliquely in one direction toward the first extending portion132. Similarly, the second extending portion 135 may include asingle-sided oblique section 173 a at a position closer to the secondopposing portion 130 and a straight-line section 173 b at a positioncloser to the second surface 102 b. The single-sided oblique section 173a extends obliquely in one direction toward the first extending portion133. The second extending portion 136 may include a single-sided obliquesection 174 a at a position closer to the second opposing portion 130and a straight-line section 174 b at a position closer to the firstsurface 102 a. The single-sided oblique section 174 a extends obliquelyin one direction toward the first extending portion 132. The secondextending portion 137 may include a single-sided oblique section 175 aat a position closer to the second opposing portion 130 and astraight-line section 175 b at a position closer to the second surface102 b. The single-sided oblique section 175 a extends obliquely in onedirection toward the first extending portion 133.

Accordingly, the first extending portions 132 and 133 preferably includethe double-sided oblique sections 170 a and 171 a extending obliquelytoward the second extending portions 134 through 137, while the secondextending portions 134 through 137 include the single-sided obliquesections 172 a through 175 a extending obliquely toward the firstextending portions 132 and 133. Thus, the electrical distance betweenthe center outer electrodes 104 and 105 and the side outer electrodes106 through 109 (for example, the distance in a path: center outerelectrode 104→first extending portion 132→first conductor layer120→dielectric layer 110→second conductor layer 122→second extendingportion 136→and outer electrode 108) is decreased. As a result, it ispossible to decrease the ESL.

Additionally, the first extending portions 132 and 133 include thestraight-line sections 170 b and 171 b, and the second extendingportions 134 through 137 include the straight-line sections 172 bthrough 175 b. Accordingly, even if the position at which the outershape of the first extending portions 132 and 133 and the secondextending portions 134 through 137 is cut is displaced in the thicknessdirection T, the widths of the exposed portions of the first extendingportions 132 and 133 and the second extending portions 134 through 137remain the same and are not increased. Thus, the exposed portions of thefirst extending portions 132 and 133 and the second extending portions134 through 137 are not connected to thin portions of the center outerelectrodes 104 and 105 and the side outer electrodes 106 through 109. Asa result, it is unlikely that moisture will permeate into thethree-terminal capacitor 100 at positions at which the center outerelectrodes 104 and 105 and the side outer electrodes 106 through 109 arelocated, thus more than sufficient ensuring moisture sealingcharacteristics.

The first conductor layer 120 and the second conductor layer 122 opposeeach other in the width direction W with the inner dielectric layer 110,which is made of a dielectric material, therebetween. At the portion atwhich the first and second conductor layers 120 and 122 oppose eachother with the inner dielectric layer 110 therebetween (portion at whichthe first opposing portion 128 of the first conductor layer 120 opposesthe second opposing portion 130 of the second conductor layer 122),electrostatic capacitance is produced. The first and second conductorlayers 120 and 122 are preferably made of Ag, Cu, Ni, Pd, or an alloy ofsuch metals. The inner dielectric layer 110 and the outer dielectriclayer 112 a preferably made of, for example, a barium titanate materialor a strontium titanate material. The average thickness of the first andsecond conductor layers 120 and 122 preferably is about 1.0 mm orsmaller, for example. For ensuring electrical continuity, the averagethickness of the first and second conductor layers 120 and 122 is about0.3 mm or greater, for example.

FIG. 10 is a schematic front view of the fifth surface 102 e of thecapacitor element 102 of another modified example of the three-terminalcapacitor 100 shown in FIG. 1. FIG. 11A is a schematic sectional viewtaken along line IV-IV of FIG. 10, and FIG. 11B is a schematic sectionalview taken along line V-V of FIG. 10. FIG. 12 illustrates the interfacebetween the outer dielectric layer 112 (212) and the outermost conductorlayer 124 (126) with a boundary layer 127 therebetween.

The thickness of the outermost conductor layers 124 and 126 preferablyis smaller than that of the first or second conductor layer 120 or 122positioned near the center of the width direction W. The thickness ofthe central portions of the outermost conductor layers 124 and 126preferably is about 0.8 mm or smaller, for example. For ensuringelectrical continuity, the average thickness of the outermost conductorlayers 124 and 126 preferably is about 0.3 mm or greater, for example.

The coverage of the conductor layers tends to be gradually thinner fromthe center to both sides in the width direction W. Accordingly, thecoverage of the outermost conductor layers 124 and 126 is thinner thanthat of the first or second conductor layer 120 or 122. The coverage isdefined by the ratio of the total length of conductor particles in crosssection to the total length of a conductor layer in cross section. Tocalculate the coverage, measurements are made by exposing a side surfacein the L direction and the thickness direction T (LT surface) of thethree-terminal capacitor 100B and by polishing the exposed side surface,for example.

Preferably, the coverage of the outermost conductor layers 124 and 126is, for example, about 0.4 to about 0.85 times as large as the coverageof the first or second conductor layer 120 or 122 near the center in thethickness direction T. In this manner, due to the intermittentconcentration of conductor particles, the coverage of the outermostconductor layers 124 and 126 is decreased, and as a result, a missingportion 126 a is produced, as shown in FIG. 11B. If the coverage of theoutermost conductor layers 124 and 126 is less than about 0.4 times aslarge as the coverage of the first or second conductor layer 120 or 122near the center in the thickness direction T, for example, it isdifficult to secure electrical continuity. Conversely, if the coverageof the outermost conductor layers 124 and 126 is more than about 0.85times as large as the coverage of the first or second conductor layer120 or 122, for example, the interlayer adhesion force is notsufficiently enhanced.

In the missing portion 126 a, a pillar 110 a that couples the dielectriclayers with the outermost conductor layers 124 and 126 therebetween isprovided. This pillar 110 a preferably contains at least one of Si, Al,and barium titanate (BaTiO₃) segregated from the dielectric layers. Suchsegregated material contained in the pillar 110 a may be analyzed andobserved by a field emission wavelength-dispersive X-ray spectrometer(FE-WDX), for example.

In order to enhance the formation of a pillar 110 a that couples theinner dielectric layers 110, SiO₂ is preferably added to the innerdielectric layers 110. The ratio of Si to Ti in the inner dielectriclayers 110 is preferably about 1.3 mol % or higher, and in order tosecure the function of a capacitor, it is preferably about 3.0 mol % orlower, for example. In order to enhance the formation of a pillar 110 athat couples dielectric layers, Al is preferably added to the dielectriclayers. In order to enhance the formation of a pillar 110 a that couplesdielectric layers, barium titanate (BaTiO₃), which is the same materialfor the dielectric layers, is preferably added to conductor layers.

The outermost conductor layer 124 is connected to the center outerelectrodes 104 and 105, as in the first conductor layer 120 disposedadjacent to the outermost conductor layer 124 with the inner dielectriclayer 110 therebetween. The outermost conductor layer 126 is connectedto the side outer electrodes 106 through 109, as in the second conductorlayer 122 disposed adjacent to the outermost conductor layer 126 withthe inner dielectric layer 110 therebetween.

As shown in FIG. 12, the boundary layer 127 in which Mg, Mn, and Nicoexist is disposed between the outermost conductor layer 124 or 126 andthe outermost dielectric layer 112. The boundary layer 127 can be formedby Mg and Mn diffused into the outermost conductor layer 124 or 126including Ni, so as to include a Mg—Mn—Ni coexistence region.

Preferably, the boundary layer 127 occupies about 69% or higher of theboundary space between the outer dielectric layer 112 and the outermostconductor layer 124 or 126, for example. The ratio of the boundary layer127 is calculated by the expression (the total length of the boundarylayer in which Mg and Mn are contained)/(the length of the conductorlayer)×100. In this case, the length of the conductor layer in theabove-described expression is a length of the conductor layer from whicha portion of the conductor layer which is missing due to voids or thesegregation of Si is removed.

In the Mg—Mn—Ni coexistence region, the molar ratio of Mg and Mn to Niis preferably about 0.1 to about 0.8, and the areal ratio of Mg and Mnto Ni is preferably about 30% or higher, and more preferably, about 70%or higher, for example.

In this manner, if the thickness of the outermost conductor layers 124and 126 is smaller than that of the first or second conductor layer 120or 122, the interlayer adhesion force between dielectric layers adjacentto each other with the outermost conductor layer 124 or 126 therebetweenis enhanced. As a result, it is possible to significantly reduce orprevent the occurrence of cracks and to significantly reduce or preventa decrease in the function of a capacitor.

If the coverage of the outermost conductor layers 124 and 126 is about0.4 to about 0.85 times as large as the coverage of the first or secondconductor layer 120 or 122 near the center in the thickness direction T,the coverage is decreased due to the intermittent concentration ofconductor particles, thus producing a missing portion 126 a, as shown inFIG. 11B. In the missing portion 126 a, a pillar 110 a is configured bya dielectric layer containing, for example, barium titanate or silica.The presence of the pillar 110 a enhances coupling between thedielectric layers disposed adjacent to each other with the outermostconductor layer 124 or 126 therebetween through particles of theoutermost conductor layer 124 or 126, thus enhancing the interlayeradhesion force therebetween. As a result, the occurrence of cracks issignificantly reduced or prevented and the function of a capacitor isless likely to be decreased.

The outermost conductor layer 124 is connected to the center outerelectrodes 104 and 105, as in the first conductor layer 120 adjacent tothe outermost conductor layer 124 with the inner dielectric layer 110therebetween. The outermost conductor layer 126 is connected to the sideouter electrodes 106 through 109, as in the second conductor layer 122adjacent to the outermost conductor layer 126 with the inner dielectriclayer 110 therebetween. In this case, the outermost conductor layers 124and 126 do not substantially contribute to the generation ofelectrostatic capacitance. Accordingly, even if cracks occur in or nearthe outermost conductor layer 124 or 126, the function of a capacitor isless likely to be decreased.

If the boundary layer 127 disposed between the outermost conductor layer124 or 126 and the outermost dielectric layer 112 includes a Mg—Mn—Nicoexistence region in which Mg and Mn are segregated, as shown in FIG.12, the boundary layer 127, which contains an oxide compound of Mg, Mn,and Ni, has a strong adhesion with a dielectric layer. As a result, theoccurrence of cracks is significantly reduced or prevented and thefunction of a capacitor is less likely to be decreased. The detection ofa boundary layer is conducted by observing a cross section including theboundary layer by using a FE-WDX, for example.

FIGS. 13A and 13B are schematic sectional views of the three-terminalcapacitor 100B of the first preferred embodiment. The center outerelectrode 105 and the side outer electrodes 107 and 109 located on thesecond surface 102 b are similar to the counterparts located on thefirst surface 102 a, and thus, they are not shown.

The length of the side outer electrode 106 in the length direction L isindicated by E1, the length of the center outer electrode 104 in thelength direction L is indicated by E2, and the length of the side outerelectrode 108 in the length direction L is indicated by E3. The distancebetween the side outer electrode 106 and the center outer electrode 104is indicated by ME1, and the distance between the side outer electrode108 and the center outer electrode 104 is indicated by ME2. The widthfrom an edge of the second extending portion 134 closer to the thirdsurface 102 c to the third surface 102 c is indicated by M1L, and thewidth from an edge of the second extending portion 134 closer to thefourth surface 102 d to the edge of the side outer electrode 106 on thefirst surface 102 a is indicated by M1R. The width from an edge of thefirst extending portion 132 closer to the third surface 102 c to an edgeof the center outer electrode 104 on the first surface 102 a closer tothe third surface 102 c is indicated by M2L, and the width from an edgeof the first extending portion 132 closer to the fourth surface 102 d toan edge of the center outer electrode 104 on the first surface 102 acloser to the fourth surface 102 d is indicated by M2R. The width froman edge of the second extending portion 136 closer to the third surface102 c to the edge of the side outer electrode 108 on the first surface102 a is indicated by M3L, and the width from an edge of the secondextending portion 136 closer to the fourth surface 102 d to the fourthsurface 102 d is indicated by M3R. Although the dimension of each of thecenter outer electrode 105 and the side outer electrodes 106 and 108 mayvary in the thickness direction, the dimensions E1, E2, E3, ME1, ME2,M1L, M1R, M2L, M2R, M3L, and M3R are all measured in the same crosssection.

In this case, the three-terminal capacitor 100B satisfies the followingconditions. The total dimension of E1+ME1+E2+ME2+E3 is greater than thedimension of the capacitor element 102 in the length direction L(hereinafter will be referred to as the “L dimension”). The side outerelectrode 106 includes the third portion 106 c on the third surface 102c, while the side outer electrode 108 includes the third portion 108 con the fourth surface 102 d. In this case, the three-terminal capacitor100B preferably satisfies |ME1−ME2|<about 50 μm, and also preferablysatisfies M2L<M2R, and M1R>M1L, or M2L>M2R and M1R<M1L.

It is preferable that the ratio of each of M1R, M2L, M2R, and M3L to theL dimension is about 1.5% or higher, for example.

The dimensions E1, E2, E3, ME1, ME2, M1L, M1R, M2L, M2R, M3L, and M3Rare measured as follows. In the state in which a side surface in thelength direction L and the thickness direction T (LT surface) of thethree-terminal capacitor 100B is exposed, the three-terminal capacitor100B is fixed. Then, the three-terminal capacitor 100B is polished untilthe depth of about ½ in the width direction W by using a polishingmachine so as to expose the first and second conductor layers 120 and122. Then, after the polished surfaces of the first and second conductorlayers 120 and 122 are worked so as to eliminate edge rounding, they areobserved from the fifth surface 102 e of the three-terminal capacitor100B by using an optical microscope, thereby measuring the dimensions,for example.

In the three-terminal capacitor 100B configured as described above, thefirst and second conductor layers 120 and 122 preferably are disposedperpendicularly or substantially perpendicularly to the first surface102 a or the second surface 102 b (in other words, the mounting surface)of the three-terminal capacitor 100B, and the stacking direction isparallel or substantially parallel with the first or second surface 102a or 102 b (in other words, the mounting surface).

Second Preferred Embodiment

FIG. 14 is an external perspective view of a three-terminal capacitor200, which is a multilayer ceramic electronic component. FIG. 15 is aperspective view of a capacitor element 202 of the three-terminalcapacitor 200 shown in FIG. 14. FIG. 16 is an exploded perspective viewof the capacitor element 202 shown in FIG. 15.

The three-terminal capacitor 200 is similar to the three-terminalcapacitor 100 of the first preferred embodiment from which the firstextending portion 133 of the first conductor layer 120 and the secondextending portions 135 and 137 of the second conductor layer 122 areremoved or are never provided. Accordingly, the three-terminal capacitor200 is similar to the three-terminal capacitor 100 from which the centerouter electrode 105 and the side outer electrodes 107 and 109 areremoved or are never provided.

The three-terminal capacitor 200 includes a capacitor element 202preferably having a rectangular or substantially rectangularparallelepiped shape, a center outer electrode 204 located at thecentral portion of the surface of the capacitor element 202, and endouter electrodes 206 and 208 respectively located at the left and rightend portions of the surface of the capacitor element 202.

The capacitor element 202 includes first and second surfaces 202 a and202 b opposing each other in a thickness direction (top-bottomdirection) T. The capacitor element 202 also includes third and fourthsurfaces 202 c and 202 d opposing each other in a length direction(right-left direction) L. The capacitor element 202 also includes fifthand sixth surfaces 202 e and 202 f opposing each other in a widthdirection (front-back direction) W.

The dimension of the three-terminal capacitor 200 in the lengthdirection L is preferably about 2.00 mm to about 2.10 mm, the dimensionin the thickness direction T is preferably about 0.7 mm to about 1.0 mm,and the dimension in the width direction W is preferably about 1.20 mmto about 1.40 mm, for example.

The dimensions of the three-terminal capacitor 200 in the lengthdirection L, the thickness direction T, and the width direction W may bemeasured by using a micrometer MDC-25MX made by Mitutoyo Corporation,for example.

The center outer electrode 204 extends from the longitudinal centralportion of the first surface 202 a to the fifth and sixth surfaces 202 eand 202 f.

The center outer electrode 204 includes a center outer electrode body204 a and first portions 204 b, 204 b. The center outer electrode body204 a is electrically connected to a first extending portion 232 of afirst conductor layer 220, which will be discussed later. The firstportions 204 b, 204 b extend from both ends of the center outerelectrode body 204 a. Accordingly, the center outer electrode body 204 ais located on the first surface 202 a, and the first portions 204 b, 204b are located on the fifth and sixth surfaces 202 e and 202 f.

The side outer electrodes 206 and 208 are respectively disposed at theleft and right end portions of the first surface 202 a with the centerouter electrode 204 therebetween.

More specifically, the side outer electrode 206 extends from onelongitudinal end of the first surface 202 a to the third, fifth, andsixth surfaces 202 c, 202 e, and 202 f. The side outer electrode 208extends from the other longitudinal end of the first surface 202 a tothe fourth, fifth, and sixth surfaces 202 d, 202 e, and 202 f.

The side outer electrode 206 includes an outer electrode body 206 a,second portions 206 b, 206 b, and a third portion 206 c. The side outerelectrode body 206 a is electrically connected to a second extendingportion 234 of a second conductor layer 222, which will be discussedlater. The second portions 206 b, 206 b extend from both ends of theside outer electrode body 206 a. The third portion 206 c extends fromone side (toward the third surface 202 c) of the side outer electrodebody 206 a. Accordingly, the side outer electrode body 206 a is locatedon the first surface 202 a, the second portions 206 b, 206 b are locatedon the fifth and sixth surfaces 202 e and 202 f, and the third portion206 c is located on the third surface 202 c.

Similarly, the side outer electrode 208 includes an outer electrode body208 a, second portions 208 b, 208 b, and a third portion 208 c. The sideouter electrode body 208 a is electrically connected to a secondextending portion 236 of the second conductor layer 222, which will bediscussed later. The second portions 208 b, 208 b extend from both endsof the side outer electrode body 208 a. The third portion 208 c extendsfrom the other side (toward the fourth surface 202 d) of the side outerelectrode body 208 a. Accordingly, the side outer electrode body 208 ais located on the first surface 202 a, the second portions 208 b, 208 bare located on the fifth and sixth surfaces 202 e and 202 f, and thethird portion 208 c is located on the fourth surface 202 d.

With the above-described configuration, the first surface 202 a definesand serves as a mounting surface of the three-terminal capacitor 200.

In this case, as shown in FIG. 17, a width B of the center outerelectrode 204 is preferably greater than a width A of each of the sideouter electrodes 206 and 208.

The center outer electrode 204 is preferably defined by applying a pastefor forming outer electrodes once, while each of the side outerelectrodes 206 and 208 is preferably defined by applying a paste forforming outer electrodes twice, for example. As a result, the thicknessof the side outer electrodes 206 and 208 is greater than that of thecenter outer electrode 204.

A plating film is located on the surface of each of the center outerelectrode 204 and the side outer electrodes 206 and 208.

FIG. 17 is an external perspective view of a modified example of thethree-terminal capacitor 200 shown in FIG. 14.

Concerning the second surface 202 b, which is the top surface of thethree-terminal capacitor 200A shown in FIG. 17, the corners of ridgelines 203 a and 203 b in the length direction L may be polished intorounded portions with an R amount of about 70 μm or smaller, and morepreferably, with an R amount of about 30 μm to about 70 μm, for example.The phrase “R amount” indicates a radius of the respective roundedportion.

In this manner, if the R amount of rounded portions of the ridge lines203 a and 203 b in the length direction L on the top surface (secondsurface 202 b) of the three-terminal capacitor 200A is about 70 μm orsmaller, the area required to suck the three-terminal capacitor 200A toa mount board by using a suction nozzle is reliably secured on the topsurface (second surface 202 b). As a result, when mounting thethree-terminal capacitor 200A on a mount board, it makes it easy for asuction nozzle to suck the top surface (second surface 202 b) of thethree-terminal capacitor 200A, thus reducing the possibility that asuction nozzle will fail to correctly suck the three-terminal capacitor200A.

If the R amount of rounded portions of the ridge lines 203 a and 203 bin the length direction L on the top surface (second surface 202 b) ofthe three-terminal capacitor 200A is about 30 μm or greater, the ridgelines 203 a and 203 b do not become angular, and are less likely to chipeven if a mechanical impact is applied to the ridge lines 203 a and 203b.

As shown in FIG. 16, the capacitor element 202 has a multilayerstructure including, in the width direction W (stacking direction), aplurality of inner dielectric layers 210, a plurality of first andsecond conductor layers 220 and 222 which are each disposed at theinterface between inner dielectric layers 210, outermost conductorlayers 224 and 226 disposed such that they sandwich the plurality ofinner dielectric layers 210 therebetween, and outer dielectric layers212 disposed such that they sandwich the outermost conductor layers 224and 226 therebetween.

The first conductor layers 220 each have a first opposing portion 228and a first extending portion 232 extending from the central portion ofthe first opposing portion 228 downward in the thickness direction T.The first extending portion 232 extends to the central portion of thefirst surface 202 a of the capacitor element 202 so as to beelectrically connected to the center outer electrode 204.

The second conductor layers 222 each have a second opposing portion 230,a second extending portion 234 extending from the left end portion ofthe second opposing portion 230 downward in the thickness direction T,and a second extending portion 236 extending from the right end portionof the second opposing portion 230 downward in the thickness directionT. The second extending portion 234 extends to the left end portion ofthe first surface 202 a of the capacitor element 202 so as to beelectrically connected to the side outer electrode 206. The secondextending portion 236 extends to the right end portion of the firstsurface 202 a of the capacitor element 202 so as to be electricallyconnected to the side outer electrode 208.

FIG. 18 is a perspective view of a modified example of the capacitorelement 202 shown in FIG. 15. FIG. 19 illustrates a first innerelectrode (first conductor layer 220) and the first extending portion232 of the capacitor element 202A shown in FIG. 18. FIG. 20 illustratesa second inner electrode (second conductor layer 222) and the secondextending portions 234 and 236 of the capacitor element 202A shown inFIG. 18.

Part (I) of FIG. 19 illustrates the first conductor layer 220 and thefirst extending portion 232 taken along line I-I (position in thevicinity of the outermost layer of the capacitor element 202A) of FIG.18. Part (II) of FIG. 19 illustrates the first conductor layer 220 andthe first extending portion 232 taken along line II-II (position in thevicinity of a layer disposed farther inward than the outermost layer ofthe capacitor element 202A by about ¼ of the width W) of FIG. 18. Part(III) of FIG. 19 illustrates the first conductor layer 220 and the firstextending portion 232 taken along line III-III (position in the vicinityof a center layer of the capacitor element 202A) of FIG. 18.

A width E of the exposed portion of the first extending portion 232 ofthe first conductor layer 220 disposed near the center layer of thecapacitor element 202A is preferably greater than a width F of theexposed portion of the first extending portion 232 of the firstconductor layer 220 disposed near the outermost layer of the capacitorelement 202A. The width of the exposed portion of the first extendingportion 232 is gradually increased from the position near the outermostlayer to the position near the center layer.

Part (I) of FIG. 20 illustrates the second conductor layer 222 and thesecond extending portions 234 and 236 taken along line I-I of FIG. 18.Part (II) of FIG. 20 illustrates the second conductor layer 222 and thesecond extending portions 234 and 236 taken along line II-II of FIG. 18.Part (III) of FIG. 20 illustrates the second conductor layer 222 and thesecond extending portions 234 and 236 taken along line III-III of FIG.18.

A width G of the exposed portions of the second extending portions 234and 236 of the second conductor layer 222 disposed near the center layerof the capacitor element 202A is preferably greater than a width H ofthe exposed portions of the second extending portions 234 and 236 of thesecond conductor layer 222 disposed near the outermost layer of thecapacitor element 202A. The width of the exposed portions of the secondextending portions 234 and 236 is gradually increased from the positionnear the outermost layer to the position near the center layer.

A description will further be given with reference to FIG. 6 used forthe first preferred embodiment. The exposed portion of the secondextending portion 234 of the second conductor layer 222 disposed nearthe center layer of the capacitor element 202A is separated from thethird surface (end surface) 202 c of the capacitor element 202A by adistance C. Similarly, the exposed portion of the second extendingportion 236 of the second conductor layer 222 disposed near the centerlayer of the capacitor element 202A is separated from the fourth surface(end surface) 202 d of the capacitor element 202A by a distance C.Meanwhile, the exposed portion of the second extending portion 234 ofthe second conductor layer 222 disposed near the outermost layer of thecapacitor element 202A is separated from the third surface 202 c of thecapacitor element 202A by a distance D. Similarly, the exposed portionof the second extending portion 236 of the second conductor layer 222disposed near the outermost layer of the capacitor element 202A isseparated from the fourth surface 202 d of the capacitor element 202A bya distance D. The distance D is preferably greater than the distance C.

In order to set the distance D to be greater than the distance C, thesecond extending portions 234 and 236 are configured as follows. Asshown in FIG. 20, the second extending portions 234 and 236 of thesecond conductor layer 222 disposed near the outermost layer of thecapacitor element 202A each include an oblique section 229, so that theexposed portions of the second extending portions 234 and 236 arepositioned toward the center (inward). Then, by setting the angle of theoblique section 229 to increase from the position of the secondconductor layer 222 near the outermost layer to the position of thesecond conductor layer 222 near the center layer, the positions of theexposed portions of the second extending portions 234 and 236 areshifted gradually toward outward.

FIGS. 21A and 21B are schematic sectional views of another modifiedexample of the three-terminal capacitor 200 shown in FIG. 14.

As shown in FIG. 21A, the first extending portion 232 may include adouble-sided oblique section 270 a at a position closer to the firstopposing portion 228 and a straight-line section 270 b at a positioncloser to the first surface 202 a. The double-sided oblique section 270a extends obliquely in two directions toward the second extendingportions 234 and 236.

As shown in FIG. 21B, the second extending portion 234 may include asingle-sided oblique section 272 a at a position closer to the secondopposing portion 230 and a straight-line section 272 b at a positioncloser to the first surface 202 a. The single-sided oblique section 272a extends obliquely in one direction toward the first extending portion232. The second extending portion 236 may include a single-sided obliquesection 274 a at a position closer to the second opposing portion 230and a straight-line section 274 b at a position closer to the firstsurface 202 a. The single-sided oblique section 274 a extends obliquelyin one direction toward the first extending portion 232.

The first conductor layer 220 and the second conductor layer 222 opposeeach other in the width direction W with the inner dielectric layer 210,which is made of a dielectric material, therebetween. At the portion atwhich the first and second conductor layers 220 and 222 oppose eachother with the inner dielectric layer 210 therebetween (portion at whichthe first opposing portion 228 of the first conductor layer 220 opposesthe second opposing portion 230 of the second conductor layer 222),electrostatic capacitance is generated.

The thickness of each of the outermost conductor layers 224 and 226 issmaller than that of the first or second conductor layer 220 or 222positioned near the center of the width direction W. The thickness ofeach of the central portions of the outermost conductor layers 224 and226 preferably is about 0.8 mm or smaller, for example. For ensuringelectrical continuity, the average thickness of each of the outermostconductor layers 224 and 226 preferably is about 0.3 mm or greater, forexample.

The coverage of the conductor layers tends to be gradually thinner fromthe center to both sides in the width direction W. Accordingly, thecoverage of the outermost conductor layers 224 and 226 is thinner thanthat of the first or second conductor layer 220 or 222. The coverage isdefined by the ratio of the total length of conductor particles in crosssection to the total length of a conductor layer in cross section.

Preferably, the coverage of the outermost conductor layers 224 and 226is about 0.4 mm to about 0.85 times as large as the coverage of thefirst or second conductor layer 220 or 222 near the center in thethickness direction T, for example. A pillar 110 a that couples thedielectric layers disposed with the outermost conductor layer 224 or 226therebetween contains at least one of Si, Al, and barium titanate(BaTiO₃) segregated from the dielectric layers.

The outermost conductor layer 224 is connected to the center outerelectrode 204, as in the first conductor layer 220 disposed adjacent tothe outermost conductor layer 224 with the inner dielectric layer 210therebetween. The outermost conductor layer 226 is connected to the sideouter electrodes 206 and 208, as in the second conductor layer 222disposed adjacent to the outermost conductor layer 226 with the innerdielectric layer 210 therebetween.

As shown in FIG. 12, a boundary layer 227 disposed between the outermostconductor layer 224 or 226 and the outermost dielectric layer 212includes a Mg—Mn—Ni coexistence region in which Mg and Mn aresegregated.

In the three-terminal capacitor 200 configured as described above, thefirst and second conductor layers 220 and 222 are disposedperpendicularly or substantially perpendicularly to the first surface202 a (in other words, the mounting surface) of the three-terminalcapacitor 200, and the stacking direction is parallel or substantiallyparallel with the first surface 202 a (in other words, the mountingsurface).

A non-limiting example of a manufacturing method for the above-describedthree-terminal capacitors 100, 100A, 100B, 200, and 200A will bedescribed below with reference to the flowchart of FIG. 22. In thefollowing description, a non-limiting example of a manufacturing methodfor the three-terminal capacitor 100 will be discussed mainly.

In step S1, slurry for forming sheets is made by adding an organicbinder, a dispersant, and a plasticizer to ceramic powder made of abarium titanate material or a strontium titanate material. Then, theslurry is formed into inner layer and outer layer ceramic green sheetsby a doctor blade method.

Then, in step S2, an Ag-containing paste for forming conductor layers isapplied onto the inner layer ceramic green sheets by a screen printingmethod so as to form conductor paste films which will be used as thefirst and second conductor layers 120 and 122.

Then, in step S3, a plurality of inner layer ceramic green sheets onwhich conductor paste films are formed are stacked and fixed on eachother with pressure such that the conductor paste films forming thefirst conductor layers 120 and the conductor paste films forming thesecond conductor layers 122 are alternately disposed. Then, a pluralityof outer layer ceramic green sheets are stacked and fixed on each otherwith pressure so as to sandwich the stacked inner layer ceramic greensheets therebetween. The resulting multilayer ceramic sheets are cutinto a size of individual capacitor elements 102, thereby forming aplurality of unfired capacitor elements 102.

In step S3, if necessary, in the state in which the mounting surface(first surface 202 a) of the unfired capacitor element 202 is held in aholder, the ridge lines 203 a and 203 b of the top surface (secondsurface 202 b) in the length direction L are barrel-polished for apredetermined time until the R amount of rounded portions of the ridgelines 203 a and 203 b will be about 70 μm, for example. Thereafter, theridge lines 203 a and 203 b may be further polished by sandblastpolishing for a predetermined time until a desired R amount of roundedportion will be obtained.

In this case, for determining the conditions for barrel polishing andsandblast polishing, a sample of the capacitor element 202 is fabricatedand the R amount of rounded portions is measured in the following mannerby using VHX series digital microscope made by KEYENCE Corporation as ameasuring device, for example.

The mounting surface (first surface 202 a) of the sample of thecapacitor element 202 is molded with a resin, and then, the ridge lines203 a and 203 b of the top surface (second surface 202 b) in the lengthdirection L are barrel-polished or sandblast-polished for apredetermined time.

Then, as shown in FIG. 23A, the polished ridge lines 203 a and 203 b areobserved with a measuring device so as to specify a start point P1 andan end point P2 of a rounded portion. Then, a center point P3 betweenthe start point P1 and the end point P2 is specified.

Then, as shown in FIG. 23B, after a circle Q passing the start point P1,the center point P3, and the end point P2 is drawn, the radius of thecircle Q is measured so as to calculate the R amount of rounded portion.

Referring back to the flowchart of FIG. 22, in step S4, after theunfired capacitor element 102 is subjected to debinding processing, itis fired so as to be formed into a sintered capacitor element 102. Theinner layer and outer layer ceramic green sheets and the conductor pastefilms are fired at the same time. As a result, the inner layer ceramicgreen sheets are formed into the inner layer dielectric layers 110,while the outer layer ceramic green sheets are formed into the outerlayer dielectric layers 112. The conductor paste films are formed intothe first and second conductor layers 120 and 122 (first and secondinner electrodes).

Then, in step S5, a first step of applying a paste for forming outerelectrodes (Ag—Pd alloy paste) to the surface of the sintered capacitorelement 102 is performed. In this first step, a paste for forming thecenter outer electrodes 104 and 105 is applied, and a paste forpartially forming the side outer electrodes 106 through 109 is applied.

When applying a paste for partially forming the side outer electrodes106 through 109 to the surface of the capacitor element 102 in the firststep, it is applied such that the center of a paste for forming the sideouter electrodes 106 through 109 is separated from the third surface 102c and the fourth surface 102 d of the capacitor element 102 toward theinward direction. By applying a paste in this manner, the side outerelectrodes 106 through 109 can be formed so as to satisfy H2>H3 andH2′>H3′.

In the first paste-applying step, a paste for forming the center outerelectrodes 104 and 105 is applied, and also, a paste for partiallyforming the side outer electrodes 106 through 109 is applied. In thismanner, the side outer electrodes are formed efficiently.

Then, in step S6, the paste applied to the capacitor element 102 to formthe center outer electrodes 104 and 105 and the paste applied to thecapacitor element 102 to partially form the side outer electrodes 106through 109 in step S5 are baked. As a result, the center outerelectrodes 104 and 105 are formed, and the side outer electrodes 106through 109 are partially formed. In this case, the thickness of thecenter outer electrodes 104 and 105 is thicker, while the thickness ofthe side outer electrodes 106 through 109 is thinner.

Step S6 may be omitted so as to directly shift the process from step S5to step S7, and the paste for forming the center outer electrodes 104and 105 and the paste for partially forming the side outer electrodes106 through 109 may be baked all together in step S8.

Then, in step S7, a second step of applying a paste for forming outerelectrodes (Ag—Pd alloy paste) to the surface of the sintered capacitorelement 102 is performed. In the second paste-applying step, a pasteonly for forming the side outer electrodes 106 through 109 is applied.

When applying a paste to the surface of the capacitor element 102 toform the side outer electrodes 106 through 109 in the second step, it isapplied such that the center of a paste for the side outer electrodes106 through 109 is separated from the third surface 102 c and the fourthsurface 102 d of the capacitor element 102 toward the inward direction.By applying a paste in this manner, the side outer electrodes 106through 109 can be formed so as to preferably satisfy H2>H3 and H2′>H3′.

Then, in step S8, the paste applied to the capacitor element 102 to formthe side outer electrodes 106 through 109 in step S7 is baked. As aresult, the side outer electrodes 106 through 109 are formed. Then, thethickness of the side outer electrodes 106 through 109 is formed thickerthan that of the center outer electrodes 104 and 105.

Then, in step S9, a Ni-plated layer and a Sn-plated layer aresequentially formed by wet plating on the surface of each of the centerouter electrodes 104 and 105 and the side outer electrodes 106 through109. As a result, the three-terminal capacitor 100 (100A, 100B, 200,200A) is manufactured.

As discussed above, in the three-terminal capacitor 100 of the firstpreferred embodiment, the center outer electrodes 104 and 105 may beused as signal electrodes, while the side outer electrodes 106 through109 may be used as ground electrodes, and vice versa.

The value of the insertion loss incurred when the center outerelectrodes 104 and 105 are used as signal electrodes and the side outerelectrodes 106 through 109 are used as ground electrodes (hereinaftersuch a pattern will be referred to as a “the first pattern”) isindicated by IL1. Conversely, the value of the insertion loss incurredwhen the center outer electrodes 104 and 105 are used as groundelectrodes and the side outer electrodes 106 through 109 are used assignal electrodes (hereinafter such a pattern will be referred to as a“second pattern”) is indicated by IL2. In this case, when thethree-terminal capacitor 100 is preferably configured to be used in afrequency band of about 10 MHz, the relationship between the insertionloss of the first pattern and that of the second pattern represented byIL1<IL2 is satisfied, and when the three-terminal capacitor 100 ispreferably configured to be used in a frequency band of about 100 MHz,the relationship between the insertion loss of the first pattern andthat of the second pattern represented by IL1>IL2 is satisfied. That is,in the 100 MHz band, the value of the insertion loss is smaller when thethree-terminal capacitor 100 is used with the second pattern than thatwhen the three-terminal capacitor 100 is used with the first pattern.

The reason why the frequency characteristics concerning the insertionloss when the three-terminal capacitor 100 is used with the firstpattern are different from those when the three-terminal capacitor 100is used with the second pattern is that the path through which a signaland noise are transmitted is different between the first pattern and thesecond pattern. This will be discussed below in detail.

FIGS. 24A through 24C are schematic diagrams illustrating the paththrough which a signal and noise are transmitted when the three-terminalcapacitor 100 is used with a first pattern. FIG. 24A is a schematicdiagram of the three-terminal capacitor 100 as viewed from the outside.FIG. 24B is a schematic diagram of the first conductor layer 120. FIG.24C is a schematic diagram of the second conductor layer 122. In FIGS.24A through 24C, the solid arrows indicate the flow of a signal, whilethe dashed arrows indicate the flow of noise.

When the three-terminal capacitor 100 is used with the first pattern, asshown in FIG. 24A, a signal input into the three-terminal capacitor 100through the center outer electrodes 104 and 105 is transmitted throughthe center outer electrodes 104 and 105 and is output from the centerouter electrodes 104 and 105. Meanwhile, as shown in FIGS. 24B and 24C,noise produced in the first pattern flows to a ground through the secondextending portions 134 through 137 of the second conductor layer 122.

FIGS. 25A through 25C are schematic diagrams illustrating the paththrough which a signal and noise are transmitted when the three-terminalcapacitor 100 is used with a second pattern. FIG. 25A is a schematicdiagram of the three-terminal capacitor 100 as viewed from the outside.FIG. 25B is a schematic diagram of the first conductor layer 120. FIG.25C is a schematic diagram of the second conductor layer 122. In FIGS.25A through 25C, the solid arrows indicate the flow of a signal, whilethe dashed arrows indicate the flow of noise.

When the three-terminal capacitor 100 is used with the second pattern,as shown in FIGS. 25A and 25C, a signal input into the three-terminalcapacitor 100 through the side outer electrodes 106 and 107 at one sideis output from the side outer electrodes 108 and 109 at the other sidethrough the second extending portions 134 through 137 of the secondconductor layer 122. Meanwhile, as shown in FIG. 25B, noise produced inthe second pattern flows to a ground through the first extendingportions 132 and 133 of the first conductor layer 120.

As a result of conducting an extensive study, the present inventors havediscovered and conceived that, by considering the fact that thefrequency characteristics concerning the insertion loss when thethree-terminal capacitor 100 is used with the first pattern aredifferent from those when the three-terminal capacitor 100 is used withthe second pattern, the first pattern or the second pattern may beselected depending on a required frequency band. Thus, the presentinventors have conducted an experiment for checking that a desirablevalue of insertion loss may be obtained by using the single signalthree-terminal capacitor 100 by changing the pattern to be used, thatis, the first pattern or the second pattern, depending on a requiredfrequency band. A description will be given below of an experiment forexamining the frequency characteristics concerning the insertion losswhen the three-terminal capacitor 100 is used with the first pattern andthose when the three-terminal capacitor 100 is used with the secondpattern.

FIG. 26 is a graph illustrating the result of this experiment. Thehorizontal axis indicates the frequency (MHz) and the vertical axisindicates the insertion loss (dB). The first pattern is indicated by thesolid line, while the second pattern is indicated by the broken line.

The graph of FIG. 26 shows that the first pattern exhibits lowerinsertion loss than the second pattern when the frequency is around 10MHz. Accordingly, if a required frequency is about 10 MHz, it ispreferable that the three-terminal capacitor 100 is used with the firstpattern (that is, the center outer electrodes 104 and 105 are used assignal electrodes and the side outer electrodes 106 through 109 are usedas ground electrodes, as shown in FIG. 24A).

On the other hand, the graph of FIG. 26 shows that the second patternexhibits lower insertion loss than the first pattern when the frequencyis around 100 MHz. Accordingly, if a required frequency is about 100MHz, it is preferable that the three-terminal capacitor 100 is used withthe second pattern (that is, the center outer electrodes 104 and 105 areused as ground electrodes and the side outer electrodes 106 through 109are used as signal electrodes, as shown in FIG. 25A).

That is, by changing the pattern to be used, that is, the first patternor the second pattern, depending on the required frequency band, adesirable value of insertion loss is obtained by using the singlethree-terminal capacitor 100.

Although an explanation is not given here, advantages similar to thoseobtained for the three-terminal capacitor 100 of the first preferredembodiment are achieved for the three-terminal capacitor 200 of thesecond preferred embodiment, and the other three-terminal capacitors100A, 100B, 200A of various preferred embodiments of the presentinvention.

The three-terminal capacitor 100 (200) preferably satisfies thefollowing conditions. The total dimension of E1+ME1+E2+ME2+E3 is greaterthan the dimension of the capacitor element in the length direction L.The side outer electrode 106 (206) includes the third portion 106 c (206c) on the third surface 102 c (202 c), while the side outer electrode108 (208) includes the third portion 108 c (208 c) on the fourth surface102 d (202 d). The three-terminal capacitor 100 (100A, 100B, 200, 200A)preferably satisfies |ME1−ME2|<about 50 μm, and also preferablysatisfies M2L<M2R, and M1R>M1L, or M2L>M2R and M1R<M1L. With thisconfiguration, the center outer electrode 104 (204) and the side outerelectrodes 106 (206) and 108 (208) are always displaced towarddetermined end surfaces. As a result, the insulation resistance betweenouter electrodes is less likely to be decreased.

In this three-terminal capacitor 100 (100A, 100B, 200, 200A), if theratio of each of M1R, M2L, M2R, and M3L to the dimension of thecapacitor element in the length direction L is about 1.5% or higher, forexample, it is possible to more reliably cover the first extendingportion 132 (232) and the second extending portions 134 (234) and 136(236) by the center outer electrode 104 (204) and the side outerelectrodes 106 (206) and 108 (208), respectively. As a result, theinsulation resistance between outer electrodes is even less likely to bedecreased.

In an experiment, samples of three-terminal capacitors were fabricatedin the following manner.

In this experiment, a sample of a three-terminal capacitor of apreferred embodiment of the present invention and a sample of athree-terminal capacitor of a comparative example for evaluatingthree-terminal capacitors were fabricated by using the above-describedmanufacturing method on the basis of the conditions indicated in Table 2and Table 3. The three-terminal capacitor of the present preferredembodiment and that of the comparative example have the same structurein terms of the design, except for the length L and the dimensions E1,E2, E3, ME1, ME2, M1R, M2L, M2R, and M3L of the three-terminalcapacitors.

The insulation resistance between the center outer electrode and theside outer electrodes of the preferred embodiment and that of thecomparative example were measured, and when the insulation resistancewas lower than 10⁷Ω, it was determined that a decrease in the insulationresistance was observed.

A humidity load test was also conducted on the three-terminal capacitorof the present preferred embodiment and that of the comparative examplein the following manner. The three-terminal capacitors were left in anatmosphere of a relative humidity of 100% RH at a temperature of 120° C.for 400 hours while a voltage of 6.3 V was being applied. Then, theinsulation resistance IR was measured, and when the insulationresistance IR preferably satisfies Log(IR)<5, it was determined that thethree-terminal capacitor was broken.

The evaluation of the insulation resistance characteristics is shown inTable 2, and the evaluation of the humidity resistance characteristicsis shown in Table 3.

TABLE 2 L |ME1 − E1 + ME1 + Insulation dimension E1 E2 E3 M1L M1R ME1M2L M2R ME2 M3L M3R ME2| E2 + resistance (μm) (μm) (μm) (μm) (μm) (μm)(μm) (μm) (μm) (μm) (μm) (μm) (μm) ME2 + E3 characteristics Preferred2005 462.21 672.81 471.8 57.2 79.4 242 30.5 60.5 250 35.2 115.3 82098.82 ◯ embodiment Comparative 2097 442.4 685.4 457.2 85.2 55.5 21062.5 28.5 272 32.5 95.1 62 2067 X example

TABLE 3 L dimension M1R M2L M2R M3L (μm) (μm) (μm) (μm) (μm) M1R/L M2R/LM2L/L M3L/L Humidity resistance characteristics Preferred embodiment2005 57.2 30.5 60.5 35.2 2.85% 1.52% 3.02% 1.76% ◯ Comparative example2017 15.8 72.3 20.5 60.5 0.78% 3.58% 1.02% 3.00% X

The results of Table 2 show that the comparative example does notsatisfy the relationships E1+ME1+E2+ME2+E3>L, |ME1−ME2|<50 μm, andM2L<M2R and M1R>M1L, or M2L>M2R and M1R<M1L. That is, the distancebetween the center outer electrode and the side outer electrodes issmall, thus decreasing the insulation resistance therebetween.

The results of Table 3 show that, in the comparative example, M1R/L isabout 0.78% and M2L/L is about 1.02%, while, in the preferredembodiment, M1R/L, M2R/L, M2L/L, and M3L/L are all about 1.5% or higherso as to obtain good humidity resistance characteristics. Concerning theevaluations of the insulation resistance characteristics, the sameresults indicated in Table 2 were obtained.

The present invention is not restricted to the above-described preferredembodiments, and may be modified in various manners within the scope andspirit of the present invention.

In the three-terminal capacitor 100 (100A, 100B, 200, 200A) of the first(second) preferred embodiment, concerning the side outer electrode 106(206) disposed at one end portion of the first surface 102 a (202 a) inthe length direction L, if the higher one of the heights of thelongitudinal central portions of the second portions 106 b, 106 b (206b, 206 b) disposed on the fifth and sixth surfaces 102 e (202 e) and 102f (202 f) is indicated by H2 and if the height of the widthwise centralportion of the third portion 106 c (206 c) disposed on the third surface102 c (202 c) is indicated by H3, the relationship between the heightsH2 and H3 preferably satisfies H2>H3. However, this is only an example.

Concerning the side outer electrode 108 (208) disposed at the other endportion of the first surface 102 a (202 a) in the length direction L, ifthe higher one of the heights of the longitudinal central portions ofthe second portions 108 b, 108 b (208 b, 208 b) disposed on the fifthand sixth surfaces 102 e (202 e) and 102 f (202 f) is indicated by H2′and if the height of the widthwise central portion of the third portion108 c (208 c) disposed on the fourth surface 102 d is indicated by H3′,the relationship between the heights H2′ and H3′ preferably satisfiesH2′>H3′. However, this is only an example.

In the three-terminal capacitor 100 (100A, 100B, 200, 200A) of the first(second) preferred embodiment, the thickness of the outermost conductorlayers 124 and 126 (224 and 226) is smaller than that of the first andsecond conductor layers 120 and 122 (220 and 222) positioned near thecenter of the W direction. However, this is only an example.

In the three-terminal capacitor 100 (100A, 100B, 200, 200A) of the first(second) preferred embodiment, the outermost conductor layer 124 (224)is connected to the center outer electrodes 104 and 105 (204), as in thefirst conductor layer 120 (220) disposed adjacent to the outermostconductor layer 124 (224) with the inner dielectric layer 110 (210)therebetween. However, this is only an example, and the outermostconductor layer 124 (224) may be connected to the side outer electrodes106 through 109 (206 and 208). Similarly, the outermost conductor layer126 (226) is connected to the side outer electrodes 106 through 109 (206and 208), as in the second conductor layer 122 (222) disposed adjacentto the outermost conductor layer 126 (226) with the inner dielectriclayer 110 (210) therebetween. However, this is only an example, and theoutermost conductor layer 126 (226) may be connected to the center outerelectrodes 104 and 105 (204).

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A three-terminal capacitor comprising: acapacitor element including first and second surfaces extending in alength direction and in a width direction, third and fourth surfacesextending in the width direction and in a thickness direction, and fifthand sixth surfaces extending in the length direction and in thethickness direction; a first-side outer electrode that is disposed at afirst end portion of the first surface in the length direction and onportions of the third, fifth, and sixth surfaces; a second-side outerelectrode that is disposed at a second end portion of the first surfacein the length direction and on portions of the fourth, fifth, and sixthsurfaces; a center outer electrode that is disposed at a portion of thefirst surface between the first-side outer electrode and the second-sideouter electrode in the length direction and on portions of the fifth andsixth surfaces; a plurality of first conductor layers that are disposedwithin the capacitor element and that include first extending portionsconnected to the center outer electrode; and a plurality of secondconductor layers that are disposed within the capacitor element and thatinclude first-side second extending portions connected to the first-sideouter electrode and second-side second extending portions connected tothe second-side outer electrode; wherein a pair of outermost conductorlayers of the plurality of the first conductor layers and the pluralityof the second conductor layers are disposed at both outermost ends inthe width direction; a first one of the pair of outermost conductorlayers next to one of the plurality of first conductor layers with onlyan inner dielectric layer therebetween is connected to the center outerelectrode; and a second one of the pair of outermost conductor layersnext to one of the plurality of second conductor layers with only aninner dielectric layer therebetween is connected to the first-side outerelectrode and the second-side outer electrode.
 2. The three-terminalcapacitor according to claim 1, wherein an outer dielectric layer isdisposed adjacent to one of the fifth and sixth surfaces and next to oneof the pair of outermost conductor layers; and a boundary layerincluding Mg and Mn is disposed between the outer dielectric layer andthe one of the pair of outermost conductor layers.
 3. The three-terminalcapacitor according to claim 2, wherein the one of the pair of outermostconductor layers includes Ni; and the boundary layer includes Ni.
 4. Thethree-terminal capacitor according to claim 1, wherein at a crosssection of the capacitor element, a ratio of a total length of conductorparticles of one of the pair of outermost conductor layers to a lengthof the one of the pair of outermost conductor layers is smaller than aratio of a total length of conductor particles of a center conductorlayer to a length of the center conductor layer, the center conductorlayer is closest to a center of the cross section of the capacitorelement in the thickness direction among the plurality of the firstconductor layers and the plurality of the second conductor layers. 5.The three-terminal capacitor according to claim 4, wherein the conductorparticles of the one of the pair of outermost conductor layers includeNi; and the conductor particles of the center conductor layer includeNi.
 6. The three-terminal capacitor according to claim 3, wherein at across section of the capacitor element, a ratio of a total length ofconductor particles of one of the pair of outermost conductor layers toa length of the one of the pair of outermost conductor layers is smallerthan a ratio of a total length of conductor particles of a centerconductor layer to a length of the center conductor layer, the centerconductor layer is closest to a center in the thickness direction of thecross section of the capacitor element among the plurality of the firstconductor layers and the plurality of the second conductor layers. 7.The three-terminal capacitor according to claim 6, wherein the conductorparticles of the one of the pair of outermost conductor layers includeNi; and the conductor particles of the center conductor layer includeNi.
 8. The three-terminal capacitor according to claim 1, wherein amaterial is provided within the capacitor element, the material couplesdielectric layers with one of the pair of outermost conductor layerslocated therebetween and includes at least one of Si, Al and BaTiO₃. 9.The three-terminal capacitor according to claim 3, wherein a material isprovided within the capacitor element, the material couples dielectriclayers with one of the pair of outermost conductor layers locatedtherebetween and includes at least one of Si, Al and BaTiO₃.
 10. Thethree-terminal capacitor according to claim 5, wherein a material isprovided within the capacitor element, the material couples dielectriclayers with one of the pair of outermost conductor layers locatedtherebetween and includes at least one of Si, Al and BaTiO₃.
 11. Thethree-terminal capacitor according to claim 7, wherein a material isprovided within the capacitor element, the material couples dielectriclayers with one of the pair of outermost conductor layers therebetweenand includes at least one of Si, Al and BaTiO₃.
 12. The three-terminalcapacitor according to claim 1, wherein the plurality of secondconductor layers are exposed at the first surface and are connected tothe first-side outer electrode and the second-side outer electrode atthe first surface; and the plurality of second conductor layers arespaced apart from the third and fourth surfaces.
 13. The three-terminalcapacitor according to claim 12, wherein the second one of the pair ofoutermost conductor layers is exposed at the first surface and isconnected to the first-side outer electrode and the second-side outerelectrode at the first surface; and the second one of the pair ofoutermost conductor layers is spaced apart from the third and fourthsurfaces.
 14. The three-terminal capacitor according to claim 1, whereina length of the first-side outer electrode in the length direction isE1; a length of the second-side outer electrode in the length directionis E3; a length of the center outer electrode in the length direction isE2; a width from an edge of the first-side second extending portioncloser to the third surface to the third surface is M1L; a width from anedge of the first-side second extending portion closer to the fourthsurface to an edge of the first-side outer electrode on the firstsurface is M1R; a width from an edge of the first extending portioncloser to the third surface to an edge of the center outer electrode onthe first surface closer to the third surface is M2L; a width from anedge of the first extending portion closer to the fourth surface to anedge of the center outer electrode on the first surface closer to thefourth surface is M2R; a width from an edge of the second-side secondextending portion closer to the fourth surface to the fourth surface isM3R; a width from an edge of the second-side second extending portioncloser to the third surface to an edge of the second-side outerelectrode on the first surface is M3L; and E1<E2, E3<E2, M2L<M2R,M1L<M1R, and M3L<M3R are satisfied.